The present invention relates to a push-button switch, a selector switch and a fixing component therefor.
Heretofore, push-button switches have been used as a switch for consumer-oriented appliances. As an example of a push-button switch, there has been known a switch described in FIGS. 8A and 8B. As illustrated in FIG. 7, the push-button switch 2 is a switch fixed to a device casing, and includes an operation unit 601 and a switch unit 701. Every time a pressing portion in the operation unit 601 is pressed, the switch unit 701 is switched between the on-state and off-state.
A push-button switch 2 is generally fitted into a hole provided on a device casing and is fixed to the device casing with the pressing portion exposed outside the device casing. Specifically, parts of the components which constitute the operation unit 601 of the push-button switch 2 serve to fix the push-button switch to the device casing. This fixing component include a flange 50, a screw attachment 70, and a support member 80 having an opening which is approximately as large as a diameter of the screw attachment 70, and a ring attachment 90 illustrated in FIGS. 8A and 8B. The flange 50 and the screw attachment 70 each are a substantially cylindrical shape and have a spring, a slider, and the like therein for achieving a piston movement of the pressing portion.
The screw attachment 70 and the ring attachment 90 can be fastened by a screw structure. In the screw attachment 70, the flange 50 is attached to the opposite side to which the ring attachment 90 is connected. The attachment of the push-button switch 2 to the device casing can be done in such a manner that the screw attachment 70 with the flange 50 attached thereto is inserted into a mounting hole formed in the device casing from the front side of the casing, and then the ring attachment is fitted into the screw attachment 70 and fastened with a hole edge of the device casing being sandwiched between a flange portion of the flange 50 and the support member 80 disposed on the back side of the device casing.
The flange 50 and the screw attachment 70 are connected by engaging a pair of triangle projections 51 formed on an outer peripheral surface of a lower portion of the flange 50 with a pair of small holes 71 provided at corresponding locations on an upper portion of the screw attachment 70.
On the other hand, in addition to the configuration of FIGS. 8A and 8B, a mechanism that connects a flange with a screw attachment is described in IDEC “Flush silhouette switch LW series control unit”, http://www.idec.com/jpja/products/Catalogs/Switches/FLUSH_LW/index.html>. Specifically, as illustrated in FIGS. 9A to 9C, fixing components of an operation unit 601 are a flange 10, a screw attachment 30, a support member having an opening which is approximately as large as a diameter of the screw attachment 30 (not shown because it is similar to the one illustrated in FIG. 8B), and a ring attachment (not shown because it is similar to the one illustrated in FIG. 8B).
At multiple points in the screw attachment 30, there is provided a guide member 31 extending along a circumferential direction on an inner peripheral surface of an upper portion thereof. At multiple points in the flange 10, there is provided a hook 13 extending along a circumferential direction on an outer peripheral surface of a lower portion thereof. The screw attachment 30 and the flange 10 are engaged by inserting each of the hooks 13 into each of the guide members 31 and rotating the flange 10 with respect to the screw attachment 30 to a dead end. Further, in proximity to an insert opening of the guide member 31 in the upper portion of the screw attachment 30, a screw fixing hole 35 is provided. A set screw 33 is screwed into the screw fixing hole 35, and, movement of the hook 13 is prevented by blocking the insert opening of the guide member 31 with the set screw 33.
However, in the technology described in IDEC “Flush silhouette switch LW series control unit”, in order to fix the flange 10 to the screw attachment 30, the set screw 33 is required for preventing the hook 13 from moving, and the number of component parts is correspondingly increased. In addition to that, in order to fix the flange 10 to the screw attachment 30 more firmly, an adhesive substance is required.
On the other hand, in the technology illustrated in FIGS. 8A and 8B, the flange 50 is fixed to the screw attachment 70 simply by inserting the flange 50 into the screw attachment 70 so that each of the projections 51 is engaged with each of the holes 71. Therefore, when a strong force is applied to the screw attachment 70, the screw attachment 70 is unable to withstand the force. In other words, when the push-button switch is attached to the device casing, the screw attachment 70 is required to be sufficiently fastened by the ring attachment 90. Therefore, due to the fastening force, the projection 51 and the edge of the hole 71 are pressed against each other, which leads to a breakage of the projections 51. Specifically, the projection 51 is broken at fastening torque 2N·m. It should be noted that by designing the projection 51 to be bigger and stiffer, the potential breakage can be reduced, but in that case, since the outer diameter of a portion including the projection 51 of the flange 50 becomes larger than the inner diameter of the screw attachment 70, the flange 50 cannot be inserted into the screw attachment 70.